for vs forEach

JavaScript performance comparison

Revision 240 of this test case created by Ken

Preparation code

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js">
</script>
      
<script>
Benchmark.prototype.setup = function() {
  var i,
      value,
      length,
      values = [],
      sum = 0,
      context = values;
  
  for (i = 0; i < 10000; i++) {
      values[i] = Math.random();
  }
  
  function add(val) {
      sum += val;
  }
  
  // custom forEach
  Array.prototype.forEach2 = function(fn, c) {
  
  	//if (this === void 0 || this === null || typeof fn !== 'function') throw new TypeError;
  
  	var t = Object(this),
  		len = t.length >>> 0,
  		nc = (c === void 0 || c === null);
  
  	for (var i = 0; i < len; i++) {
  		if (i in t) {
  			if (nc) {
  				fn(t[i], i, t)
  			}
  			else {
  				fn.call(c, t[i], i, t)
  			}
  		}
  	}
  };
  

};

Benchmark.prototype.teardown = function() {
  i = 0;
  value = 0;
  length = 0;
  values = [];
  sum = 0;

};
</script>

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
forEach
values.forEach(function(val) {
    sum += val;
});
pending…
for loop, simple
for (i = 0; i < values.length; i++) {
    sum += values[i];
}
pending…
for loop, cached length
for (i = 0; i < values.length; sum += values[i], i++) {
  
}
pending…
for loop, reverse
for (i = values.length - 1; i >= 0; i--) {
    sum += values[i];
}
pending…
for loop, cached length, callback
length = values.length;
for (i = 0; i < length; i++) {
    add(values[i], i, values);
}
pending…
for loop, cached length, callback.call
length = values.length;
for (i = 0; i < length; i++) {
    add.call(context, values[i], i, values);
}
pending…
$.each
$.each(values, function(key, value) {
    sum += value;
});
pending…
for ... in
for (i in values) {
    sum += values[i];
}
pending…
for loop, reverse, decrement condition
for (i = values.length; i--;) {
    sum += values[i];
}
pending…
for loop, reverse, pre-decrement
for (i = values.length - 1; i >= 0; --i) {
    sum += values[i];
}
pending…
for loop, assignment condition
for (i = 0, value; value = values[i]; i++) {
    sum += value;
}
pending…
for loop, assignment condition, reversed
for (i = values.length - 1; (value = values[i]) !== undefined; i--) {
    sum += value;
}
pending…
for loop, assignment condition, callback
for (i = 0; (value = values[i]) !== undefined; i++) {
    add(value, i, values);
}
pending…
for loop, assignment condition, callback.call
for (i = 0; (value = values[i]) !== undefined; i++) {
    add.call(context, value, i, values);
}
pending…
custom forEach
values.forEach2(function(val) {
    sum += val;
});
pending…

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Revisions

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